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Sizing Big Dipper Systems In
Food Service Operations
How To Size A Big Dipper® Unit
The purpose of this sizing procedure is to give a specifying engineer a simple method for determining the proper size Big Dipper unit for various food service facility applications. Many
different methods are in use today by the major code bodies for sizing grease traps. However,
the sizing for­mula utilized by most codes becomes inaccurate whenever the facility contains
a large number of fixtures. Using such sizing methods can lead to cal­culations that indicate
enormous flow rates being generated. In reality this rarely occurs because:
1) the building’s potable water supply can not produce this great of a flow rate
2) all of the fixtures can not be in use at the same time, and
3) the only fixtures that can produce high rates of flow are those that “store and release”
large volumes of water such as deep multi-compartment sinks.
The key factor to be considered when sizing a Big Dipper® Auto­matic Grease & Oils Removal
Unit is the peak flow rate*. The method shown on the sizing page takes the most commonly
used sizing method and adapts it for use in single fixture service applica­tions. An example of
a single fixture is a two or three compartment sink. An individual Big Dipper unit could be
plumbed to this type of fixture.
The multiple fixture sizing formula takes points 1, 2 and 3 above into consideration. As an illustration, the multiple fixture example describes common kitchen wash equipment and drainage requirements for a typical large full-service restaurant. Using the older multiple fixture
unit values, the peak flow rate is calculated to be 240 gallons per minute (14.14 l/s). Using
field experi­ence data and the combined method, we find that the peak flow rate for this “typical” restaurant is actually 48 gallons per minute. At 48 gallons per minute (3.03 l/s) maximum
peak flow rate, a 50 gallon per minute (3.14 l/s) Big Dipper system could easily handle the effluent discharges of this restaurant. For kitchen effluent flows greater than 50 GPM (3.14 l/s),
Big Dipper AST systems should be utilized. Big Dipper AST (Automatic Solids Transfer) centralized grease removal systems are designed for basement locations or for larger, institutionaltype kitchens such as hospitals, correctional facilities or casinos.
* Another factor to consider is that of head pressure. Big Dipper internal flow controls are acceptable to 6 feet (1.95 m) of head pressure. If a higher head pressure is present in a location,
it is recommended that a larger size Big Dipper unit be installed and the VFCA Flow Control
Vent be installed.
NOTE: Drawing for reference only. Equipment must be installed in compliance
with all applicable laws, regulations and codes, including plumbing codes.
Installation should be performed by a qualified plumber.
©2013 Thermaco, Inc. • All rights reserved • Patented/Patents Pending • Specifications subject to change without notice
12/13
646 Greensboro St. • Asheboro, N. C. 27204-2548 • Phone (336) 629-4651 • North America: (800) 633-4204
info@thermaco.com • www.big-dipper.com
1
Sizing Point Source Systems
Single Fixture Sizing Suggestions
Use this chart to help size Big Dipper equipment that will service a single fixture. Single fixture Big Dipper equipment is designed to sit on the floor beside the fixture it is servicing. For
basement installations or installations where the Big Dipper will be more than 6 feet (1.95 m)
beneath the fixture it is servicing Thermaco, Inc. recommends the next larger unit be installed
as well as installing the VFCA Vented Flow Control Assembly. Consult a licensed plumber
regading your specific requirements.
Fixture
Description
Compartment Size
Pipe Size
GPM Rating
Suggested
System
Sink
1-3* Compartments
18” x 18” x 12”D
2”
20
W-200-IS
Sink
1-4* Compartments
18” x 24” x 15”D
2”
25
W-250-IS or
W-250-AST
Sink
1-4* Compartments
24” x 24” x 15”D
3”
35
W-350-IS
Wok Range
Wok Range with 1-5 Wok Stations
2”
15
W-150-IS
Wok Range
Wok Range with 5+ Wok Stations
2”
20
W-200-IS
Pre-Rinse Station**
N/A
W-200-IS
Ventilation Hood
Use equipment manufacturer’s peak gpm rating
Other Fixtures or Appliances
Use equipment manufacturer’s peak gpm rating
* Recommendations based on standard operating procedure, draining two (2) sinks concurrently. Should three
(3) or four (4) sinks be drained concurrently, the supplied flow control will limit flow to unit’s maximum GPM rating.
For sewer districts requiring flow ratings based on ASME or PDI standards, contact Thermaco directly for full flow
rating assessment.
** Thermaco recommends the use of the FS-1 Flat Strainer or ESU-1 External Strainer Basket in combination with
the Big Dipper in pre-rinse areas.
Note: To minimize grease/detergent emulsification, plumbing dishwashers directly into the sanitary sewer line
is recommended. Consult local codes or a licensed plumber when considering plumbing a dishwasher to a
Big Dipper unit.
Single Fixture Big Dipper Equipment
Model
GPM Rating
W-200-IS20
W-250-IS & W-250-AST
25
W-350-IS35
W-500-IS50
©2013 Thermaco, Inc. • All rights reserved • Patented/Patents Pending • Specifications subject to change without notice
2
646 Greensboro St. • Asheboro, N. C. 27204-2548 • Phone (336) 629-4651 • North America: (800) 633-4204
info@thermaco.com • www.big-dipper.com
12/13
Sizing Multiple Fixture Installations
Multiple Fixture Sizing Suggestions
Use this chart to help size Big Dipper equipment that will service multiple fixtures. Use standard Big Dipper systems for cases where the Big Dipper is less than four feet beneath the fixtures being serviced. For installations where the Big Dipper is servicing multiple fixtures and
will be facing more than 6 feet (1.95 m) of head pressure use the next size Big Dipper system or
install a Big Dipper AST (Automatic Solids Transfer) Central Grease Removal System. Never
install a smaller Big Dipper system than the rated GPM the chart calculates. Consult a licensed plumber regading your specific requirements.
Multiple Fixture Flow Calculation:
Fixture
Floor Drains
3 Compartment sink
Pre-rinse Sink
Dishwasher*
Mop Sink
2 Compartment Sink
Hand Sink
# Fixtures
#
#
#
#
#
#
#
Fixture Value
(GPM)
Total Fixture
(GPM)
7.5
25
15
30
15
25
7.5
# x 7.5
# x 25
# x 15
# x 30
# x 15
# x 25
# x 7.5
Averaging
Multiplier
0.10
0.25
0.25
0.30
0.25
0.25
0.25
Flow Rating
(GPM)
# GPM
# GPM
# GPM
# GPM
# GPM
# GPM
# GPM
Example:
Fixture
# Fixtures
Fixture Value
(GPM)
Total Fixture
(GPM)
Averaging
Multiplier
Flow Rating
(GPM)
Floor Drains
12
7.5
90
0.10
9.0
3 Compartment sink
2
25
50
0.25
12.5
Pre-rinse Sink
1
15
15
0.25
3.75
Dishwasher*130300.30 9.0
Mop Sink
1
15
15
0.25
3.75
2 Compartment Sink
1
25
25
0.25
6.25
Hand Sink
2
7.5
15
0.25
3.75
Total 48 gpm
Note: Always use next larger size unit than the calculated flow rating.
In this case, a W-500-IS system would adequately handle the kitchen flow.
*To minimize grease/detergent emulsification, plumbing dishwashers directly into the sanitary sewer line
is recommended. Consult local codes or a licensed plumber when considering plumbing a dishwasher to a
Big Dipper unit.
** Thermaco recommends the use of the FS-1 Flat Strainer or ESU-1 External Strainer Basket in combination with
the Big Dipper in pre-rinse areas.
©2013 Thermaco, Inc. • All rights reserved • Patented/Patents Pending • Specifications subject to change without notice
12/13
646 Greensboro St. • Asheboro, N. C. 27204-2548 • Phone (336) 629-4651 • North America: (800) 633-4204
info@thermaco.com • www.big-dipper.com
3
IS Unit Installation Instructions for High
Head Height Situations (6 ft./1.95m)
Flow Control Vent/Air Intake
(Note: Flow Control Vent may be independent direct connect
to atmosphere or code-approved air admittance valve. To
be installed above sink flood rim.)
NEVER CONNECT TO FACILITY VENT
Drainage Piping
from Kitchen
Installations where head height is
greater than 6 feet (1.95 m)
Big Dipper VFCA Vented
Flow Control Module
(Please see Options Section
for sizing information)
Outlet Vent
(Note: Vent may be facility vent connection or
code-approved air admittance valve)
* Installation in high head height
locations requires removal of the
Internal Flow Control (small rubber cap under no-hub coupling
over the Inlet).
Big Dipper® IS Unit
Optional P-Trap
NOTE: Drawing for reference only. Equipment must be installed in compliance with all applicable laws, regulations and codes, including plumbing codes. Installation should be performed by a qualified plumber.
©2013 Thermaco, Inc. • All rights reserved • Patented/Patents Pending • Specifications subject to change without notice
4
646 Greensboro St. • Asheboro, N. C. 27204-2548 • Phone (336) 629-4651 • North America: (800) 633-4204
info@thermaco.com • www.big-dipper.com
12/13
IS System Plumbing
Installation Instructions
NOTE: Drawing for reference only. Equipment must be installed in compliance with all
applicable laws, regulations and codes, including plumbing codes. Installation should
be performed by a qualified plumber.
Fill Unit With Water Before Applying
To minimize grease build-up in piping, a Big Power
Locating the IS Unit
Dipper system should be located as close as
possible to the fixture it is serving. The system should be visible and easily accessible for
maintenance and inspection. The unit must
be in a level position. Be sure to check the
Specification Sheet for your model for the
exact clearances needed for installation. If
the system is located directly on the floor, the
bottom should be sealed to the floor with an
approved silicone type sealant. Make sure the
height above the Solids Strainer access cover
is enough to remove the strainer assembly.
Inlet/Outlet Piping
The inlet and outlet piping connections require
flexible sleeve pipe couplings. Keep outlet piping as straight as possible. Use only “sweep”
connections. Do not reduce the pipe sizing on
the outlet piping. Do not install “P” trap on
outlet connection of system. (Note: The system
already has a internal gas trap).
*Note: A P-Trap must be installed between the
Big Dipper unit and any upstream facility vent
connection
Flow Controls
Big Dipper systems MUST be filled with water
before energizing the power to the system.
Failure to do so will result in the destruction of
the electric heating element. These elements
will NOT be replaced under Thermaco’s Limited
Warranty.
Venting the Outlet
An outlet vent of at least 1/2 the diameter of the
system’s outlet or an approved air admittance
valve must be present as close as possible to the
Big Dipper outlet to prevent possible siphonage problems. Failure to provide a vent for the
system voids Thermaco’s Limited Warranty for
the system.
For High Head Height IS Unit
Applications Over 72” (1.95 m)
For installations where there is head height of
greater than 72” (1.95 meters), Thermaco, Inc.
recommends installation of the VFC-1 Vented
Flow Control supplied with the unit. Thermaco,
Inc. recommends an inlet vent on the piping
connection as close a possible to the inlet of the
Big Dipper and tied in to the facility vent. Please
see Page 4 for installation instructions.
Big Dipper systems are equipped with an internal
Do Not Use With Food Grinders, Potato
flow regulator located inside the inlet end of the
system. Verify its location and placement prior Peelers or Waste Disposal Units
If the internal solids strainer basket is not used
to connecting the inlet piping.
or if the system is connected to a Waste Disposal Unit, Garbage Grinder or potato peeler,
Thermaco’s Limited Warranty for the system
will be void.
©2013 Thermaco, Inc. • All rights reserved • Patented/Patents Pending • Specifications subject to change without notice
12/13
646 Greensboro St. • Asheboro, N. C. 27204-2548 • Phone (336) 629-4651 • North America: (800) 633-4204
info@thermaco.com • www.big-dipper.com
5
AST System Plumbing
Installation Instructions
NOTE: Drawing for reference only. Equipment must be installed in compliance with all
applicable laws, regulations and codes, including plumbing codes. Installation should
be performed by a qualified plumber.
Locating The AST Unit
To minimize grease build-up in piping, a Big
Dipper system should be located as close as
possible to the fixture it is serving. The system should be visible and easily accessible for
maintenance and inspection. The unit must
be in a level position. Be sure to check the
Specification Sheet for your model for the
exact clearances needed for installation. If
the system is located directly on the floor, the
bottom should be sealed to the floor with an
approved silicone type sealant. Make sure the
height above the Solids Strainer access cover
is enough to remove the strainer assembly.
Eductor Pump
The facility must provide a minimum 50 PSI
water supply to the Eductor pump on the AST
system. The eductor pump on the W-250-AST
is designed to handle incidental food solids of
less than 1” (25 mm) in diameter. The eductor
pumps on the W-750-AST & W-1250-AST are
designed to handle incidental food solids of
less than 1.5” (38 mm) in diameter. Non-food
products including rubber, plastic and metal
parts cannot be removed by the Eductor.
Inlet/Outlet Piping
The inlet and outlet piping connections require
no-hub type connectors. Keep outlet piping
as straight as possible. Assure that outlet pipe
has at least a slope of 1/4” per foot. Use only
“sweep” connections. Don’t reduce the pipe
sizing on the outlet piping. Don’t install “P”
trap on outlet connection of system. (Note:
The system already has a internal gas trap)
Flow Controls
Big Dipper systems are equipped with an internal flow regulator located inside the inlet
end of the system. Verify its location and
placement prior to connecting the inlet piping. If your code requires a vertical type flow
regulator, an approved control with a flow rating matching the system’s flow rate should be
used. Note: When a Big Dipper is servicing
multiple fixtures, some codes require separate
flow controls for each fixture. See page for
suggested high head height flow regulation
installation.
Fill Unit With Water Before Applying
Power
Big Dipper systems MUST be filled with water
before energizing the power to the system.
Failure to do so will result in the destruction of
the electric heating element. These elements
will NOT be replaced under Thermaco’s Limited
Warranty.
Venting the Outlet
An outlet vent of at least 1/2 the diameter of the
system’s outlet or an approved air admittance
valve must be present as close as possible to the
Big Dipper outlet to prevent possible siphonage problems. Failure to provide a vent for the
system voids Thermaco’s Limited Warranty for
the system.
Do Not Use With Food Grinders, Potato
Peelers or Waste Disposal Units
If the system is connected to a Food Disposal or
Garbage Grinder, Thermaco’s Limited Warranty
will be void.
©2013 Thermaco, Inc. • All rights reserved • Patented/Patents Pending • Specifications subject to change without notice
6
646 Greensboro St. • Asheboro, N. C. 27204-2548 • Phone (336) 629-4651 • North America: (800) 633-4204
info@thermaco.com • www.big-dipper.com
12/13
Internal Strainer (IS) System
Electrical Installation Instructions
Big Dipper Internal Strainer Series Models utilize one
24 hour time controller*. The timer is located under
the hinged lid of the motor enclosure on top of the
electrical module of Big Dipper (See Timer Operation
Instructions). The Big Dipper should only be plugged
into a properly grounded 3-prong 120 VAC outlet. If
possible, the power supply outlet for the Big Dipper
should be connected to an electrical circuit controlled
by a ground fault circuit breaker.
Electrical Panel
(Not Supplied)
120VAC @ 20 Amps,
From Ground Fault
Circuit Breaker
(Not Supplied)
This Big Dipper unit is shipped from the Factory
wired for Simultaneous Operation. This means the
Heater and Motor operate at the same time under
timer control. Continuous Heater Operation is
where the Heater is active at all times. To switch to
Continuous Heater Operation, switch the RED WIRE
on the THERMOSTAT with the BLACK WIRE. (Instructions are on the wiring Diagram in the electrical
enclosure.)
Note: The Big Dipper unit will not operate when
the electrical module is removed.
Power Cord,
Plugs Into Outlet
Duplex Outlet
(Not Supplied)
PROPERLY
DISPOSE OF
CONTENTS
DAILY
*Model W-1250-IS has two (2)
timers and two (2) electrical
modules
NOTE: Drawing for reference
only. Equipment must be installed in compliance with all
applicable laws, regulations
and codes, including electrical codes. Installation should
be performed by a qualified
electrician.
©2013 Thermaco, Inc. • All rights reserved • Patented/Patents Pending • Specifications subject to change without notice
12/13
646 Greensboro St. • Asheboro, N. C. 27204-2548 • Phone (336) 629-4651 • North America: (800) 633-4204
info@thermaco.com • www.big-dipper.com
7
Automatic Solids Transfer (AST) System
Electrical Installation Instructions
Electrical Panel
(NOT SUPPLIED)
115VAC Circuit,
From Ground Fault
Circuit Breaker
(NOT SUPPLIED)
Big Dipper models W-250-AST and W-750-AST are equipped
with one (1) 24 Hour/96 Event time controller while the W-1250AST model is equipped with two (2) time controllers. The timer
is located under the hinged lid of the motor enclosure on top of
the lid of Big Dipper (See Timer Operation Instructions). The
Big Dipper should only be plugged into a properly grounded
3 prong 115 VAC outlet. If possible, the power supply outlet
for the Big Dipper should be connected to an electrical circuit
controlled by a ground fault circuit breaker.
This Big Dipper unit is shipped from the Factory wired for
Simultaneous Operation. This means the Heater and Motor
operate at the same time under timer control. Continuous
Heater Operation is where the Heater is active at all times. To
switch to Continuous Heater Operation, switch the RED WIRE
on the THERMOSTAT with the BLACK WIRE. (Instructions are
on the wiring Diagram in the electrical enclosure.
Note: The Big Dipper unit will not operate when the electrical
module is removed.
Duplex Outlet
(NOT SUPPLIED)
Water Supply
Connection
Electrical Junction Box on
W-750-AST & W-1250-AST (Hidden)
Timer*
(Under Hinged Lid)
PROPERLY
DISPOSE OF
CONTENTS
DAILY
*Model W-1250-AST has two
(2) timers and two (2) electrical
modules
NOTE: Drawing for reference only. Equipment
must be installed in compliance with all applicable
laws, regulations and
codes, including electrical
codes. Installation should
be performed by a qualified electrician.
©2013 Thermaco, Inc. • All rights reserved • Patented/Patents Pending • Specifications subject to change without notice
8
646 Greensboro St. • Asheboro, N. C. 27204-2548 • Phone (336) 629-4651 • North America: (800) 633-4204
info@thermaco.com • www.big-dipper.com
12/13